Potential signs of ancient life in Mars rover photos

A careful study of images taken by the NASA rover Curiosity has revealed intriguing similarities between ancient sedimentary rocks on Mars and structures shaped by microbes on Earth. The findings suggest, but do not prove, that life may have existed earlier on the Red Planet.

The photos were taken as Curiosity drove through the Gillespie Lake outcrop in Yellowknife Bay, a dry lakebed that underwent seasonal flooding billions of years ago. Mars and Earth shared a similar early history. The Red Planet was a much warmer and wetter world back then.

On Earth, carpet-like colonies of microbes trap and rearrange sediments in shallow bodies of water such as lakes and costal areas, forming distinctive features that fossilize over time. These structures, known as microbially-induced sedimentary structures (or MISS), are found in shallow water settings all over the world and in ancient rocks spanning Earth's history.

Nora Noffke, a geobiologist at Old Dominion University in Virginia, has spent the past 20 years studying these microbial structures. Last year, she reported the discovery of MISS that are 3.48 billion years old in the Western Australia's Dresser Formation, making them potentially the oldest signs of life on Earth.

In a paper published online last month in the journal Astrobiology (the print version comes out this week), Noffke details the striking morphological similarities between Martian sedimentary structures in the Gillespie Lake outcrop (which is at most 3.7 billion years old) and microbial structures on Earth.

The distinctive shapes include erosional remnants, pockets, domes, roll-ups, pits, chips and cracks, which on Earth can extend from a few centimeters to many kilometers.

Although Noffke makes a tantalizing case for possible signs of ancient life on Mars, her report is not a definitive proof that these structures were shaped by biology. Getting such confirmation would involve returning rock samples to Earth and conducting additional microscopic analyses, a mission that isn't scheduled anytime in the near future.

"All I can say is, here's my hypothesis and here's all the evidence that I have," Noffke says, "although I do think that this evidence is a lot."

"The fact that she pointed out these structures is a great contribution to the field," says Penelope Boston, a geomicrobiologist at the New Mexico Institute of Mining and Technology. "Along with the recent reports of methane and organics on Mars, her findings add an intriguing piece to the puzzle of a possible history for life on our neighboring planet."

A Careful Analysis

"I've seen many papers that say 'Look, here's a pile of dirt on Mars, and here's a pile of dirt on Earth,'" says Chris McKay, a planetary scientist at NASA's Ames Research Center and an associate editor of the journal Astrobiology. "And because they look the same, the same mechanism must have made each pile on the two planets.'"

McKay adds: "That's an easy argument to make, and it's typically not very convincing. However, Noffke's paper is the most carefully done analysis of the sort that I've seen, which is why it's the first of its kind published in Astrobiology."

Overlay of sketch on photograph from above to assist in the identification of the structures on the rock bed surface. Image credit: Noffke (2105). Credit: ASTROBIOLOGY, published by Mary Ann Liebert, Inc.

"In one image, I saw something that looked very familiar," Noffke recalls. "So I took a closer look, meaning I spent several weeks investigating certain images centimeter by centimeter, drawing sketches, and comparing them to data from terrestrial structures. And I've worked on these for 20 years, so I knew what to look for."

Noffke compared the rover pictures to images taken at several sites on Earth, including modern sediment surfaces in Mellum Island, Germany; Portsmouth Island, USA; and Carbla Point, Western Australia; as well as older fossils of microbial mats in Bahar Alouane, Tunisia; the Pongola Supergroup in Africa; and the Dresser Formation in Western Australia.

The photos showed striking morphological similarities between the terrestrial and Martian sedimentary structures.

The distribution patterns of the microbial structures on Earth vary depending on where they are found. Different types of structures are found together in different types of environments. For instance, microbial mats that grow in rivers will create a different set of associations than those that grow in seasonally flooded environments.

The patterns found in the Gillespie Lake outcrop are consistent with the microbial structures found in similar environments on Earth.

What's more, the terrestrial structures change in a specific way over time. As the microbial mats form, grow, dry up, crack and re-grow, specific structures become associated with them. Here again, Noffke found that the distribution pattern in Martian rocks correspond with microbial structures on Earth that have changed over time. Taken together, these clues strengthen her argument beyond simply pointing out the similarities in shape.

In her paper, she also describes alternative processes through which these could have formed. For instance, the chips, pits and cracks could be the product of erosion by salt, water, or wind.

"But if the Martian structures aren't of biological origin," Noffke says, "then the similarities in morphology, but also in distribution patterns with regards to MISS on Earth would be an extraordinary coincidence."

Potential MISS erosional remnant on Mars (top); edge of a microbial mat–overgrown erosional remnant on Portsmouth Island, USA (middle); erosional remnant of a modern MISS on Mellum Island, Germany (bottom). Credit: Mars: NASA; Earth: Nora Noffke
"At this point, all I'd like to do is point out these similarities," she adds. "Further evidence must be provided to verify this hypothesis."

Confirmation Pending

At the end of her report, Noffke outlines a detailed strategy for confirming the potential biological nature of the Martian structures. Unfortunately, one important step—returning samples to Earth for further analyses—is just not feasible yet.

Noffke also lists a series of measurements Curiosity could potentially do to strengthen the case if it came across such structures again, including looking for organic or chemical signatures using its Sample Analysis at Mars (SAM) instrument.

But McKay says this likely would not work. "In principle, that instrument could tell us something about the nature of these materials biologically, if there were still large amounts of biological organics in the samples," he explains. "But these are just ancient sedimentary structures, and biology has long since left."

Comparison of cracks in Gillespie Lake outcrop on Mars and in a modern microbial mat in Bahar Alouane, Tunisia. Credit: Mars image: NASA; Earth image: Nora Noffke
"What's more, in practice this instrument is restricted," he adds. "There was a contamination spill in the instrument presumably during landing. So it has a very high background contamination level."

On Earth, scientists typically confirm the biological nature of microbial sediment structures by searching for specific microscopic textures, which involves cutting rocks into thin slices and studying them under a microscope.

On Mars, this would be very difficult do from an engineering perspective, although McKay doesn't rule out the possibility for future missions. "I don't know if it can be done, but engineers are pretty smart," he says. "If you give them a challenge, they usually find a solution."

He adds: "A sample return mission would be the gold standard. But that's just unlikely to happen anytime soon."

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"But if the Martian structures aren't of biological origin," Noffke says, "then the similarities in morphology, but also in distribution patterns with regards to MISS on Earth would be an extraordinary coincidence."

another classic case of confirmation bias. Those who passionately want the mythical ancient blue mars teeming with life to have really existed are the very ones who always seem to be claiming - Eureka ! We found it !

Finally a response from the science community (the paper is nearly a month old, but AGU Fall meeting came in between). And it is tentatively positive, which aligns with my notions on this when I first saw the paper.

MISS has no false negatives on Earth, and Earth is a lot more geologically complex from plate tectonics, life and hence a more locally varying climate). But of course Mars is another planet, so they have to differentiate as Noffke suggests and look for similar structure sets.

They won't make a 2 year detour to test for organics back at Yellowknife Bay. Hopefully they can catch similar structures in good conditions when they scale Gale's mountain. (In a web interview Noffke mentions having seen more structures along Curiosity's later route, but in so bad condition that she wouldn't have wanted to write a paper on those.)

@gkam: Perhaps. But likely life emerged 4.4 billion years ago on Earth, when it was as wet and cold as Mars was when the putative Yellowknife Bay formations were laid down. Of course there were the initial bombardment at the time, so something similar.

Modern pathways for life emergence are so fast that I would prefer to lay a bet on local emergence, which is also more likely than having it arise just once in similar conditions. At least I would bet that way until people have managed to investigate transpermia a lot more.

@richardwenzel987: People have "seen" things on Mars in all rover images. And mysteriously, no one has published their findings until now.

@marble89: Have you lost your marbles? Noffke however is an expert, and she didn't confirm mats, that was the test she couldn't do because she needs 9 microanalysis answers firs. She identified potential MISS fossils and went through as much of a rigorous detection that she could. (See the paper.)

Using confirmation bias for putative fossil detection was effectively killed in -06, when Brasier et al published their severe criticism on early NASA (and other) astrobiology fossil finds. You should study up on the area, since you want to be critical about it.

If you want to see rampant confirmation bias, see the Young Dryas 'impact' theory, which lost as usual when it met reality (i.e. more careful researchers). [ http://phys.org/n...act.html ]

This suggests more and more the case for a manned "telepresence" mission to Mars. Such a mission would involve setting up some kind of orbiting base, together with much-more sophisticated rovers on the surface, and maybe even devices to return samples. This would allow for human control of the robotics in near real-time, allowing far more science to be done than could be with the 40+-minute light speed travel limit from Earth. The increasing promise for Mars to hold either life or evidence of ancient life is all the more reason to be concerned about contamination, and thus why we should _avoid_ sending humans directly to the Martian surface -- thus the telepresence option -- until we know a lot more about what is there to either confirm, and then find ways to protect, present or signs of past life, or to rule that out to high levels of certainty, something for which such a mission would help greatly.

he increasing promise for Mars to hold either life or evidence of ancient life is all the more reason to be concerned about contamination, and thus why we should _avoid_ sending humans directly to the Martian surface

Any life that evolved to live specifically on mars would make short work of earth life, including possibly us. I just heard a discussion about the efficiency of humans vs rovers. A human could do in 3 minutes what a rover would need 3 weeks to do. Something like that.

In order to ensure our survival we need to establish permanent, self-sustaining colonies elsewhere in the solar system. We need to do this as soon as possible. Mars is the obvious first choice.

Only a matter of time as more and more seemingly circumstantial evidence starts to stack up to: Walks like a duck; talks like a duck; smells like a duck; and leaves behind...well you figure it out. Mars was alive, and life being what it is, like Laura Dern's scientist character on Jurassic Park said: "Life will find a way!"! Leading to my personal humble opinion that Mars DNA will probably look like verrrry ancient Earth DNA. Reasonable for how close we are and how subject to passing events that could chip off a piece of Mars and take it here, carrying its early life with it. So we are ALL Martians?!The downside is that we had better be really careful what we bring back. Most scientists think Mars life could still be there, dormant maybe, certainly frozen and dessicated on the surface; but deep down in the liquid brines in the rocks at depth probably still alive...just like some of our extremophiles. We NEED to be careful. We would look like food to similar DNA beasties

Any life that evolved to live specifically on mars would make short work of earth life, including possibly us.

not so sure about this oneIMHOif it is specifically adapted to live on Mars, it may well find Earth a little too hostile for it's survival, from other predation to the possibility that the normal atmospheric gasses might just be poisonous to it

Life living on Mars may well be better suited to adaptation to some of our extreme environs

I would love to see evidence of life from any extraterrestrial source

I wholeheartedly agree with the rest of your post. We could use orbiting platforms to build craft to go to/from Mars and the Moon, where perhaps some bases/manufacturing capabilities are built, and then commercially/scientifically explore the rest of the system using resources as we find them

RNA is pretty much constrained by its dual use as genetic and enzymatic material. (The latter it still is in DA cell ribosomes.) There are a few alternative bases, but they are harder to produce.

DNA on the other hand is one among a larger set of potential chemically stabler variants of RNA. So I don't expect to see DNA, assuming martian life still exists and evolved enough diversity to knock out the earlier RNA life.

"So we are ALL Martians?!"

I don't know if you saw my comment on that, but I argue it is generally less likely than local life emergence for obvious reasons.

"We would look like food".

They haven't evolved to feed on complex multicellulars with adaptive immune systems. They would be far more harmless than our own symbionts, like E. Coli that sometimes goes pathogenic.

if it is specifically adapted to live on Mars, it may well find Earth a little too hostile for it's survival, from other predation to the possibility that the normal atmospheric gasses might just be poisonous to it

I was responding to mikes concerns about earth life contaminating Mars. I was thinking though that Mars life might be susceptible if it is at a more primitive stage of development. One argument against finding precursor lifeforms here on earth is that more advanced life would consume or displace them. I suppose this could happen if earthlife established itself on Mars.

I would volunteer to go

Not me man. A year in a capsule the size of a living room? Full of people? I'd feel very claustrophobic. Not until we are traveling in ISS-sized vehicles.

This has nothing to do with confirmation bias. Confirmation bias would be to claim something as true based on a fit to prior, (possibly one-sided) knowledge.She's putting a hypothesis out there and making clear that it is nothing but a hypothesis - to be tested in the future.(Note the word "hypothesis". The word prefix "hypo" means "less than" in greek....as in hypochonder, hypothermia, hypocrit, ... )

Here comes the deranged fictional world of Evolutionists. They wish there is life on Mars to establish their false religion that life just simply sprouts everywhere as long as the right condition and ingredients are available. Why not bake one cake for all of us?

I'm catching a fish in this area, look there seems to some sort of corals in here... I should use interstellar microbes on my hooks to lure in Martian creatures swimming along this canyon. There is one, a big headed green Martian with two big black tantalizing eyes! Gotcha! lol

Here comes the deranged fictional world of Evolutionists. They wish there is life on Mars to establish their false religion that life just simply sprouts everywhere as long as the right condition and ingredients are available. Why not bake one cake for all of us?

Keep holding on to that thought. If this is all that is keeping you to your god delusions, then be prepared to have to give them up.

Your disappointment will be similar to those whose faith was based on the certitude that the earth was the center of the universe.

GhostofOttoTry recall who claim that the world is flat and we are the center of the universe?Let me see... Hmmm.. Ow, yes the Roman Catholic Church. And I remember Galileo almost had himself toast in hell if not from renouncing his previous statements correcting the Church on a Biblical passage that says the world is flat? Such dogma was a disgrace for science ain't it. huh.

But today this same body of faithfuls also believe that Evolution theory is a better explanation than Genesis of the Bible! lol Can you imagine that? Those who said the world is flat also believes Charles Darwin's theory! lol Hahaha. This nails the coffin then. You and the ones who said the world is flat and we're the center of the universe is in one boat! lol

Hahahaha! First find something significant before you make pronouncements!

Heres the difference bewteen religion and science: religion is based on faith, which is belief DESPITE evidence. Science on the other hand is based strictly on evidence.

We have increasing confidence in the ability of science to produce descriptions of natural phenomena. You on the other hand retain your faith despite the inability of religion to explain natural phenomena.

See the difference?

Evidence is mounting from many sources which suggest with confidence that we will soon find life on other planets. Only people blinded by faith, such as yourself, could ignore this evidence.

@paulc: "As a geologist there are other explanations (such as water driven concentrations of natural mineral "cements") to account for the localized hardened areas."

Thanks, interesting information!

If you read Nora Noffke's paper, she has a very detailed 4 step test scheme. (Where the microanalysis, and differentiation against your suggested false positives, couldn't be done, therefore the putative status of the MISS.)

The "detection" part consists of 3 different types of criteria: sedimentary structures, spatial associations and temporal successions of the features. The "identification" consists of comparison to known MISS. The "confirmation" consists of some 10-ish microscale features.

Noffke claims that already identification (the 3 criteria + comparison) has no abiotic false positives on Earth. E.g. I assume cementing would have a hard time showing the spatial associations and temporal successions that MISS does.

It's funny that you could find life that is billions of years old, especially considering the earth is at most 10,000 years old... I'd love to figure out how that works...

@christian11212000quoting creationist diatribes without evidence is just like telling us you're a ToyotaIOW - who caresyou offer NO EVIDENCE supporting your conclusions and just by the argument we can see that you are ignorant of a great deal of physics as well as geological science

I suggest you start taking some courses to learn about reality before posting again

As you will find, science and physics especially are all well founded on empirical evidence & experimental repeatable results, something which your display above cannot compete with as it is not only false, but we can dig up rocks in ANY back yard that prove this assumption a blatant lie (which is wrong according to your religion, christi... )

@christian11212000you shouldn't lie like that... because as soon as you are proven wrong you will simply revert to the whiny-crybaby look-in-the-bible tactics that all creationists doI will even links some relevant info explaining it to you with actual science which can not only be repeated, but proven (unlike your diatribe or book)http://www.tim-th...rth.htmlhttp://www.tim-th...th2.htmlhttp://www.talkor...rth.htmlhttp://infidels.o...g-earth/Please note the references provided which contain studies and empirical evidence, which i would also expect in any refute)

feel free to post equivalent evidence refuting the above, but remember to specify which study you are refuting

It's funny that you could find life that is billions of years old, especially considering the earth is at most 10,000 years old...

Think thats funny? Well consider that in order to make a 10k universe look billions of years old, your god would have had to drop every single photon in just the right place and send it on its way, so that we would look at all those distant objects and be fooled into thinking just that.

But why would he do this? Why would he go to such extreme lengths just to trick us? What kind of god LIES to us about the past in order to find out how much we TRUST him?

The same trickster who filled his book with stories about things we know never happened and people we know never existed, thats who.

How could you ever believe promises about wishes granted and eternal bliss in heaven, from a god who chooses to lie to you about everything else?

Gods are all fake, the product of tricksters and manipulators. Accept the obvious.

If my God is not real, what difference does it make to you? Believe what you want to, I know where I will spend eternity.

Because you are mentally ill or insane and should be handled as such, or treated like any child with imaginary friends. You are undiagnosed and like sociopaths do great damage with your unwillingness to separate fact from fiction

If my God is not real, what difference does it make to you? Believe what you want to, I know where I will spend eternity.

I won't speak for the Otto-Skippy, he's pretty good at doing that his self. But the difference it makes to me is peoples are always using God when they are thinking up rules for other peoples. They think if say "God wants it so", that nobody can argue back with that reason.

If God wanted it so, I would think he is smart enough to tell me him self and wouldn't need to pass it on to me third or second hand. If God can't speak for him self, then he is not much of a God don't you think? He sure do pick some doozies to do his talking for him.

@christian11212000so do iyour body will break down to it's constituent parts and become recycled back into the environmentThis is a proven fact... and there is no proof what-so-ever that you have a soul or any other means of defeating the fact that you will be worm food

It's not about seeming quite certain, either, but of demonstrated repeatable provable facts that we can show you, over and over

THAT is what SCIENCE is all about

and i really don't care about your beliefs, eitherNot unless you decide to spread your religion on a SCIENCE siteThen it becomes offensive and as it is unproven, as well as being a blatant lie (especially with regard to proven scientific facts you tried to refute above) then YOU OPENED THE DOOR to the argument

you don't like itgo TROLL elsewhere with your religionit is only real TO YOU that is why it is a FAITH, and not a SCIENCE

If my God is not real, what difference does it make to you? Believe what you want to, I know where I will spend eternity.

Well of course your god is the good one isn't he? You religionists all agree that god exists, and that he wrote wonderful books. Believers open those books and find instructions on how to treat unbelievers. These instructions include shunning, chastising, persecuting, expelling, and executing. They ALL do.

If your god is the good one, why hasn't he removed these instructions from his book? You all believe that unbelievers can't be good because it SAYS so in your book. Everyone else considers this bigotry except you, because your god says it is right and proper.

I don't know about you but I hate bigots and I resent being treated the way your god says I am supposed to be treated.

Bigots only a little more committed than yourself are strapping bombs to little girls elsewhere in the world. And their book says exactly the same things as YOURS.

But space writer Paul Abderson has contacted Noffke, and it seems the Curiosity team hasn't done their homework:

"I've been in touch with Nora Noffke regarding this re my own article(s) for my blog The Meridiani Journal as well as AmericaSpace. She doesn't think the Curiosity team (and she knows a lot of the members) has even read her full paper yet, which is lengthy and goes into a lot of detail. She also noted that no one from Space.com had contacted her re this update, to get her side. ..."